4L60e wont shift after wiring upgrade
Thread Starter
Teching In
Joined: Jul 2025
Posts: 3
Likes: 0
4L60e wont shift after wiring upgrade I am new to the forum so please bear with me.
I have a 2006 5.3LS with a 2001-2006 4L60e trans in a 48 Chevy Coe. I had a reworked wiring harness for the motor and it stopped reading the O2 sensors. We chased that for a few days and could not figure that out. Assuming a broken wire somewhere in the harness. I ordered a Gen 3 PSI harness for the truck and installed it. O2 sensors are alive and truck runs like a top, but now trans is in limp mode and the aftermarket electronic speedo has quit working. Wont shift, but will back out and drive. I have checked to see if there is power to trans plug and speedo and there is. I have checked that there is connection from the VSS sensor to the ECM. All seems good. Changed VSS sensor to be safe. Checked to make sure all wires in connectors go to appropriate places in ecm all seems good. Dazed and Confused. Does anyone out there have any idea what i can chase to sort this out. As stated, before new harness all was working with trans and speedometer but not after the installation of the PSI harness. I am new to the whole auto electric world so i may be missing something obvious.
Any help would sure be appreciated
Thank You
I have a 2006 5.3LS with a 2001-2006 4L60e trans in a 48 Chevy Coe. I had a reworked wiring harness for the motor and it stopped reading the O2 sensors. We chased that for a few days and could not figure that out. Assuming a broken wire somewhere in the harness. I ordered a Gen 3 PSI harness for the truck and installed it. O2 sensors are alive and truck runs like a top, but now trans is in limp mode and the aftermarket electronic speedo has quit working. Wont shift, but will back out and drive. I have checked to see if there is power to trans plug and speedo and there is. I have checked that there is connection from the VSS sensor to the ECM. All seems good. Changed VSS sensor to be safe. Checked to make sure all wires in connectors go to appropriate places in ecm all seems good. Dazed and Confused. Does anyone out there have any idea what i can chase to sort this out. As stated, before new harness all was working with trans and speedometer but not after the installation of the PSI harness. I am new to the whole auto electric world so i may be missing something obvious.
Any help would sure be appreciated
Thank You
TECH Junkie
Joined: May 2012
Posts: 3,042
Likes: 713
From: Poplarville, MS
It sounds as if there is something wrong whit the speed signal. I would contact PSI and/or the company that your electronic speedometer came from for help.
You could check that the wires are the same in both harnesses that go from the VSS to the PCM/TCM
You could check that the wires are the same in both harnesses that go from the VSS to the PCM/TCM
Thread Starter
Teching In
Joined: Jul 2025
Posts: 3
Likes: 0
Thank You i confirmed the wiring and all is good.